Debt snowball calculator

The calculator simulates one month at a time and stops when every balance is zero. Each month, every open debt is charged interest = round(balance × APR ÷ 12), rounded to the smallest unit of your currency and added to its balance. Every minimum is then paid, capped at the balance so a final payment can never overpay. Whatever is left of the budget goes to the current snowball target, and if that target is cleared with money to spare, the remainder cascades to the next debt in the same month.

The snowball order is fixed at the start: debts are sorted by starting balance from smallest to largest. Ties go to the higher APR, then the larger minimum, so the result is the same however you typed the rows. Because the total budget never changes, the minimum of a cleared debt automatically joins the payment on the next one; the roll-over is a consequence of a constant budget, not a separate step.

If you enter the budget as an extra amount, the calculator adds up the minimums you typed and uses budget = Σ minimums + extra. The comparison strip runs the avalanche order (highest APR first) through exactly the same simulation, and the chart’s second line runs the same simulation with the budget set to the sum of today’s minimums and nothing more. Total interest is the sum of every month’s interest charges; total paid always equals the starting balances plus that interest. The full rules, rounding and tests are on the methodology page.

Full method, rounding and tests on the methodology page

The snowball’s appeal is the first cleared account. In the worked example it happens in month 5; the avalanche clears nothing until month 16. One fewer statement to open, one fewer minimum to remember, and a visible result within a few months are the reasons people give for choosing it. Some people find that closing whole accounts helps them keep going; that is a description of how people behave, not a guarantee that it will work for you.

The cost is interest. Because the snowball ignores rates, a large balance at a high APR can sit near the back of the queue collecting interest while smaller, cheaper debts are cleared first. In the example, debt 1 at 24% receives only its 150 minimum for the first four months, and that is why it accrues 1,402.07 of interest under the snowball against 1,049.03 under the avalanche. With three debts of 8,000 at 27%, 2,500 at 19% and 900 at 9% and a budget of 600, the snowball clears the 900 in month 3 and the 2,500 in month 10, but takes 25 months and 3,426.90 of interest overall, while the avalanche takes 24 months and 2,943.53: a difference of 483.37 and one month in this scenario.

The gap depends on how far apart your rates are and whether your smallest balances also happen to be your dearest ones. When the smallest debt is also the highest-rate debt, both orders start in the same place and the difference shrinks or vanishes. The calculator shows the actual gap for your figures rather than a rule of thumb, and the debt payoff calculator puts both orders side by side with the same inputs.

The payoff order table lists your debts in snowball order with the start balance, the minimum, the month (or date, if you entered a start month) it is cleared and the interest it collected along the way. The first debt cleared stat is the snowball’s headline feature, so it sits beside the total interest. The comparison strip gives the avalanche’s months and interest on the same inputs and states the difference in plain words; it is there so the choice is made with the number in view.

The balance chart plots the total owed at the end of each month under the snowball against a second line labelled “today’s minimums, fixed”. That line keeps paying the sum of the minimums you entered every month and nothing more. In the example that is 200 a month, which takes 65 months and 5,315.88 of interest; the snowball at 500 a month takes 18 months and 1,422.37. The line is a fixed-payment comparison, not a model of a card issuer’s declining minimum; the credit card minimum payment calculator models that for a single card.

Two warnings can appear. If your total budget is below the sum of the minimums, the calculator names the shortfall instead of producing a plan. If a debt’s minimum is less than its first month’s interest, it is flagged as never repaid at the minimum: that debt only starts to fall once it becomes the snowball target, which can be a long time if it also has a large balance.

Your numbers stay in your browser. DebtWren works out your results on your device. We don’t send the balances, rates or payments you type to our servers or store them. If you allow analytics, we record only broad ranges (for example “£2,000–£5,000 of debt”) to understand how the calculators are used. Like any website with ads, this page also loads advertising scripts; see our Privacy Policy.

The calculator is plain code running in this tab. It makes no network requests with your figures, and nothing is saved when you leave unless you choose to keep it. Read the privacy policy for how ads and analytics work on this site.

• Consumer Financial Protection Bureau — How to reduce your debt (highest rate first and smallest balance first)
• Consumer Financial Protection Bureau — What is a credit card interest rate? What does APR mean?
• Consumer Financial Protection Bureau — The minimum-payment box on a credit card statement
• Federal Reserve — Consumer Credit (G.19) statistical release

Estimates for general information only — not financial, credit or legal advice. Your actual figures depend on your lender’s or card issuer’s exact terms, fees, minimum-payment rules, interest calculation method and any changes they make. Check your statements and speak to a qualified adviser before making decisions. The snowball order is chosen by balance only; we assume the payments, minimums and rates you enter stay fixed for the whole plan.

Page reviewed October 9, 2026 by the DebtWren team · Methodology · Changelog · Report an error